One data point doesn't prove anything, but nonetheless this is interesting.
I re-did the prediction for the 8 Feb '04 solar transit photographed by John
Locker, based upon his updated elevation above sea-level of 86 feet (versus 50
feet).
A - travel distance (miles) and direction
B - date
C - time
D - elevation angle of the ISS
E - azimuth angle of the ISS ( + is East from North; - is W from N)
F - range (miles)
G - latitude for observing the transit
H - longitude
I - how far (miles) can I be from the centerline?
A------- B----- C----- D--- E----- F--- G------- H-------- I----
3.9 SW 8 Feb 122740 21.6 -179.8 545 53.3561 -3.1708 5.8
0.0 SW 40.79 53.3874 -3.0919 5.8
1.0 NE 8 Feb 122741 21.5 -179.7 545 53.3957 -3.0711 5.8
The above used the Mission Control Center TLE that was posted on February 5:
1 25544U 98067A 04038.55066812 .00020000 00000-0 20000-3 0 9029
2 25544 51.6274 270.7867 0007082 138.3390 221.8310 15.66877780 17367
Next, I used the last Orbital Information Group TLE that John provided to me,
which preceded the transit by 3.34 hours, or basically 2 orbits:
1 25544U 98067A 04039.37920139 .00012863 00000-0 12391-3 0 1508
2 25544 51.6289 266.5703 0007449 140.3946 216.4560 15.66900537297940
This produced the following transit track:
A------- B----- C----- D--- E----- F--- G------- H-------- I----
0.4 W 8 Feb 122742 21.6 -179.7 545 53.3867 -3.1024 5.8
0.2 NW 42.07 53.3895 -3.0954 5.8
4.6 NE 8 Feb 122743 21.5 -179.6 546 53.4262 -3.0025 5.8
Working out the distance more precisely, the OIG track indicated that John was
about 1090 feet SE of the nearest point on the center line, while the MCC track
indicated that he was about 60 feet (!) NE of the center line.
As nearly as I can measure (and that's probably no better than +/- 100 feet),
John was actually about 200 feet NE of the closest point on the center line, so
the MCC prediction was "off" by about 140 feet... which is to say, about half
the width of the ISS's solar panels! (It'd be nice if the MCC TLEs were always
this good.)
The angular error in the OIG prediction amounts to about 0.5 minutes of arc,
though had the pass been nearly overhead, the error would have been about 1
minute of arc.
Incidentally, if anybody's ever gotten a pic of the ISS any closer to the center
of the sun or moon, I'm not aware of it.
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